The deployment of electrical submersible pumping (ESP) assemblies within an adjacent guide tube is common practice in oil production wells. These systems enable equipment, for example equipment lowered on a wireline, to safely bypass the ESP assembly to the well below. The ESP assembly typically comprises a discharge head, a pump, a protector and electrically powered motors.
In use, the motor activates the pump to pump fluids from within the well casing to the surface via production tubing. The rotation of the motor and the pump causes vibration which can result in the adjacent bypass tubing unscrewing from its threaded connection to the production tubing which is normally jointed with parallel screw threads via a Y-block.
To prevent the bypass tubing from unscrewing and falling into the well, clamps are positioned at a variety of locations along the length of the ESP assembly to rigidly clamp the ESP assembly to the adjacent bypass tubing preventing it from rotating and unscrewing from the Y-block.
These clamps are also utilized to secure electrical cables connecting the ESP assembly within the well casing.
During operation the ESP assembly, particularly the motors, heat is generated which can lead to longitudinal expansion of the ESP assembly. Fluids passing the ESP assembly absorb heat generated by the ESP assembly, preventing an equivalent temperature rise in and similar longitudinal expansion of the bypass tubing. The rigid connections formed by the clamps between the bypass tubing and ESP assembly prevent unhindered longitudinal expansion of the ESP assembly, giving rise to undesirable bending stresses within the individual sub-assemblies of the ESP. Bending of the ESP sub-assemblies resulting from these undesirable stresses may result in excessive wear on shaft bearings and other components within the ESP sub-assemblies, leading to premature failure of the sub-assemblies and ultimately the ESP assembly in its entirety.
Substantial financial losses are incurred by such failures due to the costs of equipment replacement and to loss of production from the well.